Glass plaque



P 1 955 c. H. GODDARD 2,706,353

GLASS PLAQUE Filed Sept. 27, 1949 IN VEN TOR.

(bar/es H. Goddard ATTORNEY United States Patent GLASS PLAQUE Charles H. Goddard, Newburyport, Mass.

Application September 27, 1949, Serial No. 118,173

2 Claims. (Cl. 40-130) I This invention relates to glass plaques for the conveying or preservation of information and particularly for such plaques and also as grave markers or with monuments, or as signs in stores, oflices and the like.

An object of the invention is to provide a permanent record of information and particularly to form it in a glass of the photographic type, in whichthe image is formed directly in the glass itself.

A further object is to provide a clear record of printed letters in such glass.

Still another object is to provide reflecting means for directing light passing through said plaque back to illuminate the same.

Other features, objects and advantages of the invention will be apparent from the following specification taken in connection with the accompanying drawings in which:

Figure l is a perspective view of the device according to the invention;

Figure 2 is a sectional view through a device according to the invention;

{figure 3 is a bottom view of the device of Figure 2; an

Figure 4 is a view of a type of lettering which may be used showing its depth in the glass, although for convenience in the drawing the letters are shown dark and the background clear which is opposite to that in the preferred mode of my invention.

Although the invention will be described with respect to a particular embodiment, this is merely by way of explanation and not by way of limitation, as the invention is applicable to a variety of embodiments.

In Fig. 1, the glass plate 1 will have photographed into itself the image or record to be preserved, for example a photograph of a person to be remembered and below it whatever lettering may be desired to give, say, a biographical account. This plate may be a copper-containing glass irradiated by ultraviolet light through a photograph of the intended person and through a mat bearing the proper lettering, and may be afterwards heated to the softening point to fix the image in the glass. Suitable glass, and its method of treatment for this purpose, is shown, for example, in U. S. Patents 2,422,472, and 2,326,012, issued to Robert H. Dalton. The irradiated portion of the glass may turn red, for example, and produce a reproduction of the design on the mat.

Treatment of this type produces a reproduction in depth, that is the image produced extends into the glass for a considerable distance, as for example the letter R in Fig. 5. This produces a satisfactory image when viewed directly normal to the glass, but if there is a considerable amount of such lettering, as may be present in the devices herein described, the depth of the letters makes the lettering illegible or difficult to read when the lettering is dark on the transparent background. I have found, however, that if the lettering is done in the negative form, with clear or light letters on a dark background, then the dark background obscures the depth of the lettering and makes it easier to read, particularly when viewed at an angle. To produce such an effect, the mat or screen used over the glass during irradiation should pass light everywhere except through the actual letters which are to be reproduced.

This technique of making the final image in effect a negative is not necessary, or even desirable, in the reproduction of pictorial matter, and of course a single "ice mat can be used to make such pictorial matter come out positive" and the lettering negative on a single irradiation.

The back 4 of plate 1, that is the side which is not t? be viewed, should ordinarily be frosted for best res ts.

The hollow glass box 2 should be sealed or otherwise fixed to the glass plate 1 forming therewith a hollow enclosure. A reflecting coating 3, of metal or of some other suitable material should be placed on said glass box 2, preferably on the interior surface thereof, which is preferably sand blasted to diflusely reflect light back against the glass plate 1 to illuminate the image thereon. The light which is reflected will have originally entered the box 2 through the plate 1, that is the source of illumination will be external to the device, for example being sunlight, general room illumination, or the like. If desired of course, a special external illuminator may be used, but does not appear to be necessary. The roughened reflecting surface 3 spreads the reflected light over a variety of angles, and apparently by successive reflections back and forth in the hollow of the box, provides uniform illumination on plate 4 despite the use of metal, being itself of a specular reflecting nature, in the reflector 3.

Instead of a box 2 of glass or other material having a reflecting coating 3 thereon the device may be made as shown in Figures 2 and 3 with a metal reflecting box 5, the glass plate 1 being secured thereto for example by the shelf 6 extending around the box and the bead 7. The metal box 5 preferably has slanting sides 8 into re-entrant bottom with slanting portions 9, to insure the most expeditious and uniform reflection of light against the glass plaque. The bottom surface of the glass plate is preferably frosted and the reflected interior surface of the metal box 5 roughened to better diffuse the light. This achieves a uniform illumination of plate 4, although uniformity of illumination would not be expected with such specular reflecting surfaces.

Although the glass box 2 in Figure 1 is shown rec tangular it may have slanting sides as shown for the metal reflector of Figure 2. The reflecting surface 3 may be made of a diffusely reflecting material such as paint, enamel or powder coat-ing if desired. In some cases it might be desirable to place such a diffusely reflecting coating over the interior surface of the metal box 5 for example as in Figure 2.

Although I do not wish to be restricted to any particular size of glass plate 1, I have found a size about 12" x 12" and /2" thick to be very convenient. With such a plate I find that a distance of about 2' is satisfactory for the depth of the hollow box 2 in Figure l or 5 in Figure 2. The bottom 11 of the hollow box 2 in Figure 1 or the bottom 9 of the hollow box of Figure 2 must be spaced from the inside surface 4 of the glass plate 1 in order to achieve the proper illumination of said plate 1.

The glass plate 1 may be fixed or sealed mechanically to the hollow box 2 or 5 or may be sealed directly by heating as in the usual glass-to-glass or glass-to-metal seals with the use of a glass frit or solder if desired. The seal is preferably of ahermetic nature in order to be proof against deterioration of the reflecting surfaces 3, 8, by atmospheric conditions.

If there is no image photographically set into the glass plate 1 but if one or more of its flat surfaces are frosted, preferably the inner surface as in 4, the device may be used as an instrument for colored or other photographic transparencies or plates which may be placed on the top surface of the plate 1.

What I claim is:

l. The combination of a flat glass plate having an image set photographically therein and having a roughened bottom surface to diffuse light passing therethrough, and a hollow empty reflecting bottom piece fixed to said plate and having a roughened surface to diffusely reflect light back through said glass plate, the entire bottom surface of said reflector being reentrant.

2. The combination of a flat glass plate having an image set photographically therein and having a roughened bottom surface to diffuse light passing therethrough,

reentrant.

References Cited in the file of this patent UNITED STATES PATENTS I Child Mar. 16, 1880 McGrath Dec. 11, 1917 Wertz Apr. 1, 1919 10 4 Brackensay Jan. 28, 1930 Kellogg' June 23, 1931 Thompson Feb. 23, 1932 Bergen Jan. 8, 1935 Evans Sept. 10, 1940 Dalton Aug. 3, 1943 Palmquist July 18, 1944 Dalton June 17, 1947 Bonnet Mar. 7, 1950 

